The present invention relates to gas turbines of the combined Brayton-Rankine cycle type and particularly to the integrated type in which part or all of the shaft work necessary to drive the Brayton cycle compressor is supplied by the Rankine turbine. Engines of this cycle arrangement have been described in Peterson U.S. Pat. No. 2,955,422.
Combined Brayton-Rankine cycle engines are known to be one of the most thermodynamically efficient of all heat engines. Heretofore, these engines have been used in stationary applications for electric power generation and in marine applications for the propulsion of large ships. These engines are large and complex with little or no mechanical integration between the Brayton gas turbine and Rankine steam turbine components and controls. Also, the Rankine condensers have been water cooled with a separate cooling water sub-system. In general, it would not be practical to scale down these power plants for mobile or vehicular application or where installation space was at a premium, such as on offshore oil rig platforms.
The present invention defines in part a unique integration and arrangement of mechanical components of a combined cycle engine such that the overall package is compact and suitable for mobile application, particularly for wheeled vehicular propulsion. The design features an air-cooled condenser with an engine-driven cooling fan configured to improve cooling effectiveness and reduce parasitic fan power load. The engine turbomachinery components, including the Brayton compressor and turbine, the Rankine turbine and feed pump, and the condenser cooling fan are mounted on a common axis. The heat exchangers have an annular core configuration and are concentrically mounted with the common engine axis. A centrally located engine reduction gearbox is driven by the Brayton power turbine and provides a reduced speed output shaft on an axis parallel to but offset from the primacy engine axis. Also, the gearbox is located at the approximate center of gravity of the engine.
The present invention has as its overall object to improve gas turbine engines, particularly of the integrated combined cycle Brayton-Rankine type. Another object is to provide an efficient and compact Brayton-Rankine combined cycle engine which has a unique integration and arrangement of components. A further object is to provide improved and unique components for such an engine.